1. Field of Invention
The present disclosure relates to an engine-mount, and more particularly, to an engine mount provided with all of properties of an pneumatic mount and a hydro mount (liquid enveloped-type mount).
2. Description of Related Art
Generally, vibrations are produced structurally in an engine for a vehicle and are produced also due to an uneven road surface while a vehicle drives.
The vibrations are produced not due to only one factor but due to several factors and thus the vibrations are produced up-downward, left-rightward and front/rearward.
Furthermore, an engine for a vehicle is not separated from a vehicle body but is connected to a shift device and an air conditioning device, etc., and thus the vibrations produced from the engine affect entirely the vehicle.
Accordingly, the engine for a vehicle is installed to a frame of a vehicle body through an engine mount so as to dampen the vibrations produced from the engine.
Here, an pneumatic engine mount has a damping force using air entry and exit wherein it has relatively low loss coefficient (vibration damping performance is relatively low), but the loss coefficient exhibits evenly on a wide frequency region (vibrations on wider frequency band are dampened), and a liquid enveloped-engine mount (hydro mount) has a damping force using flow resistance of hydro liquid that is enveloped therein wherein it has relatively great loss coefficient (vibration damping performance is relatively high), but the loss coefficient exhibits on a narrow frequency region (vibrations on narrower frequency band are dampened), with respect to the engine mount
In designing the liquid enveloped-engine mount of the two types of the engine mount, the engine mount has been developed to focus on dampening generally the vibration components having a frequency band region of 10-13 Hz even though there are a little differences depending on the characteristics of a vehicle, however, it has been developed for the frequency width exhibiting the loss coefficient to be wider than the frequency band region as described above, considering the frequency movement depending on a design deviation and the aging of the components including the engine mount.
However, a technology is necessary for improving to dampen vibration over the relative narrower frequency band region in a case of the liquid enveloped-engine mount, as described above.
Furthermore, a frequency of the vibration (T1 vibration or shake vibration) caused from air vibration of a tire, which is produced while a vehicle drives, is moved depending on a speed of a vehicle, producing a frequency with a great displacement. For example, when the speed of a vehicle is on 60 km/h section, a frequency of 7 Hz is produced, when the speed of a vehicle is on 100 km/h section, a frequency of 13 Hz is produced, and the speed of a vehicle is on 140 km/h section, a frequency of 18 Hz is produced wherein the frequency of the vibration is varied depending on the speed of a vehicle. However, when the vibration having a frequency of 13 Hz is produced by chance on 100 km/h section, since the frequency is the same as the frequency with the loss coefficient of the liquid enveloped-engine mount, and the vibration with a great displacement can be dampened efficiently but its effect is minute at different speeds.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.